Geometric versus Probabilistic Shaping for Circular-QAM with Nonbinary LDPC Codes
Résumé
This paper studies new geometrically shaped circular quadrature amplitude modulation (CQAM) constructions that can approach the Gaussian capacity. Then, we compare the performance of obtained constellations with existing Gaussian shaping strategies for regular and some simple optimized non-binary protographs. We also investigate the potential benefit of additional probabilistic shaping on the proposed CQAMs.